Vibration apparatus



Oct. 7, 1947. E. L. KENT ETAL VIBRATION APPARATUS Filed May 9, 1944Patented Oct. 7, 1947 VIBRATION APPARATUS Earle L. Kent, Elkhart, Ind.,and Robert C. Treseder, Dayton, Ohio; said Kent assigner to C. G. Conn,Ltd., Elkhart, Ind., a corporation of Indiana Application May 9, 1944,Serial No. 534,830

12 Claims.

The invention described herein may be manufactured and used by or forthe Government for governmental purposes, without the payment to us ofany royalty thereon.

This invention relates to vibration apparatus and more particularly to adevice having a tunable reed for measuring vibrations.

One of the objects of the invention is to provide vibration apparatuswhich is simple in construction and which can be tuned to any desiredresonant frequency within the range of the apparatus.

Another object of the invention is to provide vibration apparatus inwhich the reed may be tuned by movable supports engaging the reed andfixed guide plates beside the reed. According to one desirable feature,the resonant frequency of the reed may be indicated by the position ofthe supports.

Still another object of the invention is to provide vibration apparatusin which the reed is shaped to cause a substantially straight linevariation in resonant frequency with changes in effective length.

The above and other objects and advantages of the invention will be morereadily apparent from the following description when read in connectionwith the accompanying drawing, in which- Figure 1 is a perspective viewof a vibration measuring instrument embodying the invention;

Figure 2 is a longitudinal central section of the instrument;

Figure 3 is a horizontal section on the line 3-3 of Figure 2;

Figure 4 is a transverse section on the line 4--4 of Figure 2; and

Figure 5 is a partial transverse section of an alternative guideconstruction.

As shown on the drawing the instrument comprises a base I which may be acasting having spaced sides II of reduced height for a portion of theirlength, a cover I2 open at its ends may t over the Ibase and be securedthereto by screws I3 to enclose the operating parts. One end of thecover is closed by an end flange I4 on the base and the other end by atransparent plate I fitting at its edges into slots in the (sides I I.As shown the plate I5 is graduated into a Vertical scale, one side ofwhich may be marked for direct reading and the other for reading in amirror I6 pivoted to the cover.

A flexible vibratory reed I'I is mounted on the base, being secured atone end to the reduced portions of sides II and extending longitudinallyof the base With its other end free to vibrate adjacent the plate I5.The free en d of the reed may be weighted by strips I8 if desired, theweighting depending upon the frequency range of the instrument. It willalso be understood that the frequency range may be controlled by varyingthe length and stiffness of the reed.

The reed is adapted to be tuned by adjusting its eiective length and forthis purpose a block I9 is supported on a screw 2| which is rotatablymounted in the base and has a thumb wheel 22 outside of the end ange I4.The block is threaded on the screw to be moved longitudinally of thebase and reed as the screw is turned. An angular extension 23 is securedto the block and forms therewith a yoke straddling the reed withsupporting rollers 24 carried by the block and extension and engagingthe opposite faces of the reed.

The rollers 24 are rigidly held against vertical movement rigidly toclamp the reed by guide plates 25 of the same thickness as the reedsecured to the reduced portions of sides II and lying in the same planeas the reed when it is in its normal or neutral position. The rollers 24span the gap between the edges of the reed and guide plates and arepressed iirmly against the guide plates so that as the yoke is moved therollers clamp the reed at diilerent points in its length to vary itseffective length and consequently its resonant frequency. Preferably theextension 23 is made resilient to exert a spring clamping force throughthe rollers on the reed and guides so that they will be rmly grippedregardless of slight Variations in thickness.

In order to support the reed so that it will not buckle when the rollersare moved toward its fixed end and so that the part of the reed betweenthe rollers and fixed end of the reed will not vibrate, the block I9 andextension 23 may fit closely against the opposite faces of the reedslidingly to clamp it between them. Preferably the block and extensionclear the reed slightly and have pads 20 of yielding material such asfelt cemented to their faces and engaging the reed. In this way the reedis held against buckling when the block is moved longitudinally thereofand at the same time the part of the reed between its mounted end andthe rollers is held against vibration,

The adjusted frequency of the reed may be indicated by providing in thecover an elongated slot 26, having scale graduations along its length,through which a reference mark on or the edge Qi 1211.@ block I9 may beobserved. The scale graduations may be calibrated in terms of frequencyso that a direct reading of the adjusted frequency of the reed isobtained.

We have found that the relationship between the free length of astraight reed and its resonant frequency does not follow a straight lineand in order to produce a straight line relationship so that the scaleon the slot 26 may be uniform the reed is shaped to provide differentsections at different points in its length. It is preferable to make thereed of uniform thickness so that the reed and guide plates 25 may beplane plates of the same uniform thickness and may, if desired, be cutfrom a single sheet. Accordingly the reed is shaped by cutting away itssides as shown in Figure 3 at 21 so that the reed has a minimum widthadjacent its mounting on the sides H and tapers out to full Widthadjacent the forward ends of the guide plates 25. With the reed shapedas shown so that its sides are bowed out slightly, its free length andreso- A nant frequency have a straight line relationship so that thescale on the slot 26 can be uniformly graduated. For a non-linear scalein which the graduations are spaced wider at one part than at anotherother reed shapes may be employed.

Figure 5 illustrates an alternative guide plate structure, parts thereincorresponding to like parts in Figures 1 to 4 being indicated by thesame reference numerals. In this construction, each of the guide platesis formed by a pair of thin plates 29 bowed in transverse section andclamp at one edge on the casing sides Il so that the opposite edges tendto spring apart as shown. Each of the plates 29 is of approximately halfthe thickness of the reed, preferably being slightly less than half thereed thickness, so when the plate edges are pressed together, the totalthickness will be substantially the same as the reed thickness.

With this construction the rollers will press the edges of the plates 29together and at the same time will rmly clamp the reed. If there is anyvariation between the reed thickness and the total thickness of theguide plates the rollers will clamp the reed tightly and will be rmlyheld by the resilient action of the plates.

In using the device the base I0 is placed in contact with a vibratingmember so that the vibrations thereof will be transmitted to the reed tocause it to vibrate. When the reed is so adjusted that its resonantfrequency is different than the frequency of the vibrations itsamplitude of vibration Will be quite small. By turning the thumb screw22, the resonant frequency of the reed can be adjusted to be the same asthe frequency of the vibrations at which time the vibration of the reedwill be maximum as observed on the scale on the transparent end platel5. At this time the frequency of the vibration is indicated by theposition of the yoke relative to the scale on the slot 26 and theamplitude thereof can be observed directly on the scale on the endplate. It will be understoo-d that instead of reading the amplitudedirectly on the end plate any desired transmission means might beemployed to obtain remote readings such, for example, as the pickupapparatus more particularly described and claimed in either of ourcopending applications, Serial Nos. 534,831, led May 9, 1944, or534,832, filed May 9, 1944.

While one embodiment of the invention has been shown and described indetail herein, it is understood that this is illustrative only and isnot intended as a definition of the sope of the 4 invention, referencebeing had to the appended claims for this purpose.

What is claimed is:

1. Vibration apparatus comprising an elongated vibratory reed xedlymounted at one end with its other end free to vibrate, a guide platelying beside the reed and in the plane of the reed when the reed is inits neutral position, supporting members engaging the opposite sides ofthe reed and guide plate, and means to move th'e supporting memberslongitudinally of the reed thereby to vary the effective length of thereed.

l2. Vibration apparatus comprising an elongated vibratory reed fixedlymounted at one end with its other end free to vibrate, guide plates onopposite sides of the reed lying in the plane of the reed when it is inits neutral position, supporting members engaging the opposite faces ofthe reed and guide plates, and means to move the supporting memberslongitudinally of the reed to vary its effective length.

3. Vibration apparatus comprising an elongated vibratory reed xedlymounted at one end with its other end free to vibrate, guide plates onopposite sides of the reed lying in the plane of the reed when it is inits neutral position, supporting rollers engaging the opposite faces ofthe reed and guide plates, and means to move the rollers longitudinallyofthe reed to vary its effective length.

4. Vibration apparatus comprising a casing, a reed supported at one endin the casing with its other end free to vibrate, guide plates xedlymounted in the casing beside the reed, a yoke member slidably mounted inthe casing, supporting members carried by the yoke member and engagingthe opposite faces of the reed and plates, means to move the yoke memberlongitudinally of the reed to vary the effective length of the reed, andcooperating indicia on the casing and yoke member to indicate theresonant frequency of the reed when the yoke member is in differentpositions.

5. Vibration apparatus comprising an elongated flat reed secured at oneend with its other end free to vibrate, the reed being of substantiallyuniform thickness and varying in width from a point adjacent its securedend to a point spaced therefrom, guide plates of the same thickness asthe reed on the opposite sides thereof and lying in the plane of thereed when it is in its neutral position, supporting members engaging theopposite faces of the guide plates and reed, and means to move thesupporting members longitudinally of the reed to vary its effectivelength.

6.. Vibration apparatus comprising an elongated flat reed of uniformthickness substantially throughout its length secured at one end withits other end free to vibrate, the width of the reed varying from aminimum adjacent said one end to a maximum at a point spaced therefrom,and adjustable supporting means engaging the reed on its opposite facesand movable lengthwise thereof to vary its effective length whereby theresonant frequency of the reed and its effective length will have asubstantially straight line relationship.

7. Vibration apparatus comprising an elongated flat reed of uniformthickness substantially throughout its length secured at one end withits other end free to vibrate, the width of the reed varying from a.minimum adjacent said one end to a maximum at a point spaced therefrom,guide plates lying on opposite sides of the reed, supporting meansengaging the opposite faces of the @MM M0011 reed and guide plates, andmeans to move th'e supporting means longitudinally of the reed to varyits eifective length.

8. Vibration apparatus comprising an elongated iiat reed of uniformthickness substantially throughout its length secured at one end withits other end free to vibrate, the width of the reed varying from aminimum adjacent said one end to a maximum at a point spaced therefrom,guide plates lying on opposite sides of the reed, supporting meansengaging the opposite faces of the reed and guide plates, means to movethe supporting means longitudinally of the reed t0 vary its effectivelength, and means to indicate th'e position of the supporting means andthereby the resonant frequency of the reed.

9. Vibration apparatus comprising an elongated at reed secured at oneend with its other end free to vibrate, guide means including a pair ofresilient plates of substantially half the thickness of the reed securedface to face beside the reed with their edges adjacent the reed tendingto spring apart, and supporting means engaging the opposite faces of thereed and guide plates and squeezing said edges of the guide platestogeth'er.

10. Vibration apparatus comprising an elongated iiat reed secured at oneend with its other end free to vibrate, guide means including a pair ofresilient plates of substantially half the thickness of the reed securedface to face on each side of the reed with their edges adjacent the reedtending to spring apart, supporting means extending transversely of thereed and engaging the opposite faces of the reed and guide platestogether, and means to move the supporting means longitudinally of thereed.

11. Vibration apparatus comprising an elongated iiat reed, meansmounting the reed adjacent one end leaving its oth'er end free tovibrate. a support movable longitudinally of the reed, rollers carriedby the Support engageable with the opposite faces of the reed to varyits effective length as the support is moved, and parts on the supportengaging the opposite faces of the reed between the mounting means androllers.

12. Vibration apparatus comprising an elongated flat reed, meansmounting the reed adjacent one end leaving its other end free tovibrate, a support movable longitudinally of the reed, rollers carriedby the support engageable with the opposite faces of the reed to varyits effective length' as the support is moved, and yielding pads carriedby the support and engaging the opposite faces of the reed between themounting means and rollers.

EARLE L. KENT. ROBERT C. TRESEDER.

REFERENCES CITED The following references are of record in the le ofthis patent:

UNITED STATES PATENTS Number Name Date 1,687,507 Perkins Oct. 16, 19282,301,291 Kolesnik Nov. 10, 1942 2,356,229 Dunlap et al Aug. 22, 1944185,728 Cook Dec. 26, 1876 2,260,210 Bourne Oct. 21, 1941 2,296,213Kretzschmar Sept. 15, 1942 FOREIGN PATENTS Number Country Date 440,319Great Britain Dec. 24, 1935 548,403 Germany Apr. 15, 1932 181,880Switzerland June 2, 1936

